Biochar and Biocoal from Orangic Waste
Hydrothermal Carbonization
The Science & Engineering
Hydrothermal Carbonization (HTC) is the Earth’s natural process to produce peat, capture and recycle carbon, and generate coal. It is an exothermic reaction resulting in dehydration and decarboxylation of a material, which raises the total carbon content by removing water (H₂0). HTC occurs at relatively low temperatures (150–280°C) in a wet environment under saturated pressure (18-25bar).
Biocoal, Biochar, Liquid Fertilizer
Engineering
The choice to make a carbon neutral biocoal or a carbon sequestering biochar or soil is a local and simple choice - typically based on economics, personal needs, and legislation. The HTC processing operation is the same with time, pressure, and heat being adjusted to engineer the desired output. Only citric acid is added to manage pH and optimise the process. That right's - no chemicals!
Importantly, the liquid separated from the solids is high in nutrients and should be used as a fertility product. If this is not possible, the liquid can be readily processed on site with filtering, aerobic or anaerobic solutions, or sent to sewer directly.
Again - HTC is flexible and each implementation is driven by local economics, law, and personal requirements.
Mass Balance
Bio-waste can be generally classified as
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Water content
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Inorganic content
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Organic content
Example bio-wastes include:
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Organic Municipal Solid Waste (food, etc.):
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64% water, 36% organic
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Waste Water Sludge:
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78% water, 12% organic, 10% inorganic (sand/grit)
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Focusing on the organic fraction, the simple formula is
C6H12O6 is changed via HTC to:
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C6H2O (coal/char) + 5*H2O (water) + ENERGY
Applying this to the mass balance:
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The Organic MSW becomes:
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82% water and 18% coal/char;
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Sewage sludge becomes:
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84% water and 6% coal/char and 10% sand
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Crucially:
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The HTC reaction is Exothermic which Loritus will use to generate a self sustained continuous process.
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The output is hydrophobic and makes the output easy to filter to less than 40% moisture
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The output is broken at a molecular level, making it easier to separate inorganics such as sand and grit.
This creates huge advantages for transportation, storage, co-firing with other biomass and wood chips, as well as designing new carbon solutions with unique needs.
What can't be overlooked is the compact nature of an HTC facility. The foot print of a Loritus HTC facility will generally be 20% a composting or biogas facility, while offering the added advantage of not requiring intensive preparation - such as sorting and drying - and not producing residual waste.
A Loritus HTC facility starts at 8000 tons/yr and can readily fit in the corner of an existing property, or be designed into a disused building. Below are some examples of projects we have worked on.
Image processing 50,000tons/year on less than 3,000m³ of land - that is the organic waste from about 35,000 people!
Disused Drying Facility with high ceilings
Disused Composting Facility w/ bunker
